Let's take a quick look at all the new features that this update brings and a video tour as well. At the moment, Windows Phone 8.1 Update 2 is only available out of the box on the Lumia 640 and Lumia 640 XL, but Microsoft has confirmed Windows Phone 8.1 Update 2 'GDR2' for select handsets, including the Lumia 735 and Lumia 830. Availability is currently unknown, but it's in the works.